Chisel for mortise project - what size?

graywings123April 22, 2013

I want to install some sash pulleys in some old windows and will need to mortice out an area for each faceplate. (There is nothing there now, they are guillotine windows.) I am looking at buying one very good chisel for this one time project. What size chisel do I buy to do this?

Since the face place is 1 inch wide, do I get a one inch wide chisel? Or narrower? I found a butt chisel on the internet. What do you think? Would someone with small hands have more control with a shorter chisel like this?

I understand that I have to drill out the area for the housing. This question is about what's best for mortising around the opening for the housing.

"I want to install some sash pulleys in some old windows and will need to mortice out an area for each faceplate."

Drill a hole the correct diamter top ad bottom for each pulley.

Use a jig saw to cut betweentem to make the opening.
Check the pulleys, many are designed fr a reound ed.

Making the shallow recess for the edges of a pulley to rest in is done with a chisel less than half the width of the opening so you can concentrate on one side without touching the other.

Slide the pulley in the hole and use a sharp utility knife to outline the recess required. Remove the pulley.

Use a chisel bevel down to remove the wood to the depth needed.
It\f you are n experienced woodworker with good hand skills you could cut the whole recess before anything else.
The chisel would be the same width as the recess needed.

It is a harder way to do it if you are inexperienced.
Faster if you are experienced.

The chisel needs to be sharp enough to shave hair off the back of your hand or arm.

If you have not worked wood before like this, go buy some 1x4 from the lumber yard and practice first.

The longer chisel always gives more control.
If you have a round end to mortise, use a forstner drill bit of the exact size. Cut those before drilling though the jambs for the pulley body.
For graving in the edges of a pulley, you probably need only 1/2 or even 3/8.
I like the blue-handled Marples chisels, if they still make them.
Casey

Irwin bought or merged with Marples so I think they're called Irwin "Blue Chip" now. I have a set of older Marples and they're pretty decent but I have no idea how the current version performs. Robert Sorby makes nice chisels too.

Casey, I love the idea of using a forstner bit to mortice the top and bottom. I haven't purchased the pulleys yet, so I could switch to the rounded top instead of the squared off ones. That would only leave the sides to chisel by hand.

" That would only leave the sides to chisel by hand."
Cut them with a jig saw or keyhole saw if you want a hand tool.
Through holes are NOT really mortises.

Something that cuts on the pull stroke (like a jig saw) will result in cleaner back edges to the hole, and any slight damage on the face will be removed when you cut the shallow rebate around the hole.

You need a relatively slow sped drill to start a decent size Forstner bit.
The entire outer edge hits the wood at same time so you do not want it spinning very fast. (and tilting it makes it even worse when first starting).
You need to use a pretty decent amount of force to make sure the bit does not slip out of position.
The brad in the center helps, but only if you are pushing on the bit hard enough.
You can then reduce the force slightly after it has cut about 1/16 inch deep ad the edges are guiding the bit and let the bit do the cutting work.

A modified version of the Forstner with a screw center is used for large rough boring at low RPM for large holes required for DWV lines.
The screw center holds things in place.

I would use a brad point bit with decent cutting spurs for something like this.

Cheap brad points often do not have any actual cutting spurs ground on them and create tear-out at the cross grain edges of the the being drilled.

Any slight tear out you would have should be removed when you cut the rebate for the edges of the pulley housing.

The recess around the curve now becomes the hard part (especially when the stop bead between the upper and lower sashes gets in the way).

It actually sounds like you have double hung windows.
i have never heard them referred to as "guillotine" but it would be sort of descriptive.

Have you considered Pullman spring balances?
They fir \t in the same type of hole used by a sash pulley and weight system, but use a sprig in a housing and thin steel tapes to attach to the window.

I mount the metal tabs Pullman supplies on the sides of the window in a shallow recess so they do not show.
hammer the formed rib in the metal flat in two spots, drill and countersink fr flat head screws, a hidden attachment tab.

For older windows the weight pockets can be filed with the best insulation you can find.
Layers of R7 per inch rigid foam board work well.
Just cut strips that must be gently force in, then top them with some low expanding foam.

Wow, that's a lot to absorb. The problem I see with using any tool with a base, such as a jig saw or a router, is that the work area is inset 1/2 inch so the tool would not sit flat, one side or the other is going to fall into the inset unless I construct a base. I was hoping to use a router attachment on my Dremel, but after lots of investigating, I found that it wouldn't work because the bits are not long enough to include the 1/2 inch drop. That was when I decided to hand mortice.

Maybe there is a better name for these windows. They are 100+ year old wood windows on the back of the house that are identical to the ones with pulleys and weights. If you want to have the window open, you prop it open. If you take the prop away, 16 pounds of wood and glass drops.

I considered the Pullman spring balances, but since they also need to be recessed, they didn't appear any easier to install.

Unfortunately I'm having a hard time visualizing what you're trying to do but if you're trying to balance a tool on a narrow edge, the easiest solution is to clamp a board or boards to workpiece to increase the surface area. Festool makes a jig for its routers but it's obscenely expensive. Woodhaven used to offered one as well.

I'm installing a pulley system into the side of a window frame as in this photo. The area where the pulley goes is 1.5 inches wide and indented 0.5 inch, surrounded by sash beads. The sash beads will hold off the jig by that 0.5 inch.

In this picture, you are looking at the pulley for the bottom sash. The top sash is at your left.

I could expose the whole area by removing the top sash and removing the sash beads so that I could get a router or jig saw in there, but I can see how doing the morticing around the edges of the pulley with a hand chisel might be a lot easier. (By the way, I did not paint the inside frame where the pulley is.)